Help: improve XZ compression method docs

Relates: #27429

Help/cpack_gen/deb.rst

@@ -293,7 +293,7 @@ List of CPack DEB generator specific variables:
     Lempel–Ziv–Markov chain algorithm
 
   ``xz``
-    XZ Utils compression
+    XZ Utils LZMA2 (Lempel–Ziv–Markov chain algorithm, version 2) compression
 
   ``bzip2``
     bzip2 Burrows–Wheeler algorithm

Help/cpack_gen/rpm.rst

@@ -255,7 +255,7 @@ List of CPack RPM generator specific variables:
     Lempel–Ziv–Markov chain algorithm
 
   ``xz``
-    XZ Utils compression
+    XZ Utils LZMA2 (Lempel–Ziv–Markov chain algorithm, version 2) compression
 
   ``bzip2``
     bzip2 Burrows–Wheeler algorithm

Help/manual/cmake.1.rst

@@ -1460,7 +1460,7 @@ Available commands are:
 
     .. versionadded:: 3.1
 
-    Compress the resulting archive with XZ.
+    Compress the resulting archive with XZ (LZMA2).
 
   .. option:: --zstd